Misfire Module B

I initially suggester Brake Cleaner as it does not evaporate as quickly as Starter fluid but still leaves no residue.

If you are worried about the windscreen,  use windscreen cleaner if yours is a spray.

Otherwise, Water with a few drops of dish soap to keep it from beading up will also work.

You just need something that forms a film, gets into everywhere, and will plug the leak temporarily or disrupt the mixture.

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Actually, watching the carb balance will tell you if you have an intake leak.

Spray or Balance; you need to do it when it is running rough.

You can't fix something when it "ain't broke"!

Hi Bill,

I finished putting the engine back together with the new EGT probes and a new voltage regulator.   Wow 14.3 volts now instead of 13.7 and the EGTs work.  Did the carb balance which only needed a minor adjustment on the left carb to get an almost perfect balance.  Put the vacuum balance tube back in place and did a runup.  The ignition check was flawless and I was so excited.  Tried it several times and it all sounded great.  Shut it down and after a final visual inspection I re-cowled it and was ready for a test flight.  Start up was instant and it ran like a top..  When the temps reached normal, I moved to the runup and ignition check and found a great A side, but about a 200 RPM drop on B.  Wow. tried it again and it got worse.  Soon I was back to intermittent hard miss on B which included about a 400 rpm drop and running rough as a cob.   I tried the choke trick and although the RPM was effected, the intermittent miss on B remains.  I am totally at a loss and fresh out of ideas.  Anybody want to buy an RV-12 real cheap?  Anyway, I am totally frustrated and done for today, .......Tom 

And when it was "Running Rough as a Cob" What did those new Working EGT Probes indicate???

I didn't want to guess, so I waited until I could run it again to be more accurate with my EGTs

I had a buddy watching the engine for shake and monitoring the tailpipe while I ran it.  He is a retired auto mechanic and in most cases is a pretty good wrench, but he knows nothing about a Rotax..  He said that he noticed the engine shake from the miss.  He also said that during warm up, which is closer to idle, that the exhaust was running pretty black  and rich.  After warm up and at higher rpms, even during ignition checks, the exhaust looked good.  As far as temps go, early in the warm up the temps were running pretty close to each other within 10 degrees.  Later and during the really rough stages, the right EGT was running about 200 degrees hotter.  Our plan is to see if we can nail it down to a particular cylinder by using a laser temp gun from the get go, before the cylinders get a chance to even out in an attempt to isolate it.  I'll let you know how that goes.  ....Tom

By the way, from my buddy's experience as an auto mechanic, and doing the simple listen and watch analysis, he would be leaning towards an electrical issue , rather than carburation.  ......Tom